8 sweet Italian sausages (1 1/3 lb. total)
1 large onion, cut lengthwise into 1/4-inch-thick slices
1 medium to large fennel bulb (sometimes called anise), fronds chopped, stalks removed, and bulb halved, cored, and cut into 1/4-inch-thick slices
1 teaspoon salt
2 tablespoons extra-virgin olive oil
Prick sausages and cook in a heavy skillet over moderately low heat until browned on all sides and cooked through, about 20 minutes.
While sausages are simmering, cook onion, fennel bulb, and salt in oil in large nonstick skillet over moderately high heat, stirring, until softened, about 8 minutes. Cover skillet and cook, stirring occasionally, until tender, about 8 minutes more. Stir in fennel fronds and serve mixture with sausages.
Note: If you prefer, substitute assorted sweet peppers for fennel and serve on sausage rolls.